New and rare Cenomanian crabs (Crustacea, Decapoda, Brachyura) from the Paris Basin (France), and a comparison with necrocarcinids, etyids and dynomenids from Devon (England)

The crab fauna from the lower Cenomanian of Normandy and Sarthe is rich and diverse. Species rarely observed and two new necrocarcinids are described. Necrocarcinus inornatus sp. nov. is distinguished by its very weakly developed tuberculation, and Paranecrocarcinus pusillus sp. nov. has an ornament that differs from any other species of the genus. A comparison between the lower Cenomanian crab faunas of Petreval (Normandy) and Wilmington (Devon) shows that the faunas are similar, all species restricted to one of the areas being rare or very rare species. Species from the Cenomanian of Petreval, in common with those from Devon, show a remarkable agreement in specific characters, and, when an estimation is possible, in intraspecific variability.